The total number of warrants granted to intercept communications – for example, phone-taps and opening mail – was 3,372 in 2012, a 16% increase on 2011.
Meanwhile, the number of errors in these intercepts increased by 30% to 55. The reasons for these errors include storage of communications without legal authorisation, wrongful reactivation of interception, and failure to cancel a warrant for interception.
GCHQ made eight errors – slightly more than MI5, MI6 and the Serious and Organised Crime Agency, which made seven errors each.
The total number of requests to gather communications data – the ‘address’ information within communications – was 570,135 in 2012, a 15% increase on 2011.
In gathering this information, 979 errors were made – a proportional reduction from 0.18% in 2011 to 0.17% in 2012.
Most errors were a result of agencies using incorrect communications addresses or of gathering communications data in the wrong time period.